Bioprospecting of exopolysaccharide-producing bacteria from different natural ecosystems for biopolymer synthesis from vinasse

Abstract

Background: Exopolysaccharides (EPSs) belong to a family of organic thickeners or alternative hydrocolloids of microbial origin. Because the chemical structure offers beneficial bioactive functions, biocompatibility and biodegradability, EPSs are used in the chemical, food, pharmaceutical, cosmetics, and packaging industries as well as in agriculture and medicine. In this study, new bacterial strains were selected on the basis of their ability to synthesize EPS from substrate containing vinasse as a nutrient source to identify the best candidate for bio-based polymer production. Results: Among the 99 newly identified bacterial strains isolated from different natural ecosystem, the strain Azotobacter chroococcum 76A was selected as the best biopolymer producer since it synthesized the highest concentration of EPS in all media containing vinasse. The maximum EPS concentration (44.6 ± 0.63 mg/50 mL) was observed at 24 h, corresponding to its sub-stationary growth phase (7 × 10 8 ± 0.29 CFU/mL). Chemical characterization of the EPS produced showed that carbohydrates representing the principal component, followed by uronic acids and proteins. Interestingly, comparing the IR spectrum of the EPS with alginate by FTIR-ATR analysis revealed an overlap of a peak identified as guluronic acid, a component of alginate. Conclusions: The potential biotechnological capacity of A. chroococcum 76A to synthetize biopolymer from vinasse, inexpensive starting materials, represents a possible alternative to expensive disposal of agri-food waste through its transformation into high value-added products.

Effectiveness of Plant Beneficial Microbes: Overview of the Methodological Approaches for the Assessment of Root Colonization and Persistence

“…SEM observations have also highlighted the production of exopolysaccharides by A. chroococcum. These polymers improve the survival of EPSproducing microbial cells in natural ecosystems, exhibit beneficial effects in plant growth promotion and abiotic stress (Gauri et al, 2012;Van Oosten et al, 2017) and could be interesting for biopolymer production (Ventorino et al, 2019). Although SEM produces 3D images, it provides information only on surface morphology and colonization and is not as powerful as transmission electron microscopy (TEM).…”

Role and perspective of Azotobacter in crops production

“…The concentration of EPS which is secreting outside the cell environment depends on the carbon source. Azotobacter excreted 0.84 mg L -1 -7.5 g L -1 of EPS in liquid inorganic or organic media; and the concentration of EPS becomes higher in the presence of N (Emtiazi, Ethemadifar, & Habibi, 2004;Khanafari & Sepahei, 2007;Ventorino et al, 2019).…”

Eksplorasi Bakteri Penghasil Eksopolisakarida dari Rizosfer Kelapa Sawit sebagai Pemantap Agregat Tanah [Exploration of exopolysaccharide-producing bacteria from Oil Palm Rhizosphere as a Soil Aggregate stabilizer]

“…Gula sederhana seperti sukrosa dan glukosa pada media tumbuhmemiliki fungsi sebagai komponen pembentuk sel dan sumber energi yang dibutuhkan untuk sintesis dan ekskresi senyawa eksopolisakarida. Dengan tercukupinya kebutuhan tersebut, maka eksopolisakarida dapat dihasilkan secara optimum (Ventorino et al, 2019).…”